rapid charge retrofit?

[jadnashuanh]

Some people have unrealistic expectations about the i3. It's a great car for what it's designed for. Complaining about it's performance when used outside of those parameters is just misguided and misplaced.

 

[ultraturtle]

Some people have unrealistic expectations about the i3. It's a great car for what it's designed for. Complaining about it's performance when used outside of those parameters is just misguided and misplaced.

Happy to agree.

 

[MarkN]

The linked BMW University documents (thanks KurtEndress!) have all sorts of interesting info. 12_W20 Engine section 10.1 describes Exhaust-gas test mode:

10.1. Exhaust-gas test mode

It is necessary to start the combustion engine for an exhaust-gas test in the BMW I01 with range extender. This is made possible by a certain operating sequence:
• Tailgate is open
• Switch on ignition and engage drive position "P" (without braking)
• Press and hold down the accelerator pedal within 60 seconds
• Press the brake three times within 20 seconds and hold
• Release the accelerator pedal and press the START-STOP button when the brake is actuated
• The combustion engine starts if the SOC of the high-voltage battery is less than 75 %.

As a Check Control message the status "Exhaust-gas test mode activated" is output when the combustion engine is running. The empty run point is automatically approached during the warm-up phase. Using the pedal sensor position two speed points of the combustion engine are selected for the measurement.

The "Exhaust-gas test" mode is automatically ended:
• after 20 minutes
• or at the start of the journey
• or by switching off the ignition.

If the engine runs at full speed, one could add over 7 KWh to the battery charge during a 20 minute stop. Does anyone with a REx want to try it?

 

[KurtEndress]

I might also guess that a 4300 RPM / 34 hp / 25 kW limit may well be imposed upon North American i3s in order to maintain its astonishing 39 mpg EPA rating.

Note that the output power of the ICE engine isn't equal to the electric output of the generator. Right under that diagram the document mentions that the 94% efficiency of the "e-machine" reduces the 25kW to 23.5 kW. Both the generator (REEM) and inverter (REME) have coolant lines, so some of the power of the ICE is lost at each stage before it becomes DC electrical power to the battery.

BTW, I found that link to the BMW University documents in the forums here, posted by jackt in the "How to get the app to work?" thread.

 

[bxb40]

So one could charge a little before climbing a mountain, while eating a sandwich...

 

[jadnashuanh]

You might want to do it while out of the car. While the REx is small, and pretty clean, with the rear hatch open, if the wind was right, it might end up blowing all of the exhaust fumes into the car!

 

[KolorMeCarbon]

This thread went off-topic, still interested in the DC retrofit for my BEV. I've not found a good source of a parts diagram 'microfiche' which would help us see the exploded views of components.

Having explored the i3's motor-bay, things look far less intimidating under the hood than my old ICE vehicles. I haven't heard of anyone 'bricking' their i3's ECU either, so a DiY charging-socket retrofit isn't such a scary thing. From the minor dismantling I have done (and watched on YouTube) BMW appear to have kept much of the wiring harness common to different models. I have a 2015 BEV and an 2017 ReX which have different accessories in each car there are unterminated wires which are redundant where an accessory hasn't been factory-fitted.

 

[ecoangel]

Yes it should be possible - but be very careful - make sure you turn off main supply at front under hood before working with those orange cables!

 

[Joff]

I have looked around and not seen any evidence that anyone has completed a DC fast charge retrofit, even on other brands. A very basic diagram of how the DC charge is supposed to work, just shows the wires from the socket going to the BMS on the battery, instead of the onboard charger as it does for AC. That seems deceptively simple. I haven't seen anything that indicates that the BMS different on one version than the other, but maybe it is. Something has to communicate to the charger? Some years from now I would like to install a battery from a wrecked later model I3 with more AH and include the connection to the DC fast charge socket. I think there will be more information in the future when more of these cars are out of warranty and more people start hacking them. Good luck and let us know if you learn how!

 

[KolorMeCarbon]

Thanks for keeping the thread alive. I've been checking the RealOEM site and looking at some (non BMW) D.i.y. EV conversions, the cabling does seem to go direct to the battery from the socket. The car's sensors still monitor the LoC and communicate it back to the EVSE.

I have another i3, with a dual T2/DC socket to compare the cabling, but it's a Rex and the cable routing isn't straightforward.
I'm not going to risk connecting a new socket and cabling yet, (I've learnt some expensive lessons already with BMW's electrical system). My next call is going to be to an EV conversion specialist to gather some more info.

With the rate the UK charging infrastructure is improving, I'm not sure if the mod is worth doing or is it better to wait for 3rd-party solid-state (or other new tech) batteries to appear, and just replace all the charging system for something faster than 7kW.